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Mohamed Hagahmed, MD, EMT-P
Mohamed is an Emergency Medicine Physician and EMS director. His main areas of interest are Critical Care, Ultrasound, Prehospital Resuscitation, and Medical Education. Find him on Twitter @HagahmedMD
Etiology
- The classic clinical presentation of Neurogenic Shock is shock (hypotension) with warm extremities and bradycardia after a trauma causing a Spinal Cord Injury above the level of T6.
- Bradycardia is more common in higher cervical injuries.
- Neurogenic Shock is different than Spinal Shock which manifests as transient flaccid paralysis and loss of sensation distal to the level of injury and lasting days to weeks before spontaneous resolution of symptoms.
Management
- Prepare to secure the airway if the patient presents with signs of respiratory compromise. This can be secondary to polytrauma, airway edema or hematoma expansion as well as high cervical spine injuries resulting in diaphragmatic paralysis.
- Prompt surgical intervention as soon as the injury is identified.
- Avoid aggressive IV fluid.
- Initiate a vasopressor early. Norepinephrine is a first-line agent here. Current evidence recommends maintaining of MAP of 85-90 mmHg.
- Carefully watch and correct for hypothermia, which can develop secondary to systemic vasodilation.
The Debrief
- Neurogenic Shock is a diagnosis of exclusion. Consider it in your trauma patient with unexplained hypotension and bradycardia after ruling out hemorrhage or other internal injuries (Tension Pneumothorax, Pericardial Tamponade, etc.)
- In elderly patients, factors such as medications (Beta Blockers) or age-related neurocognitive deficits can mask the severity of their symptoms. Maintain a low threshold for considering spinal injuries in these patients.
References
- Mapelli E, Sabhaney V. “Neurogenic Shock.”Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 8eEds. Judith E. Tintinalli, et al. New York, NY: McGraw-Hill, 2016, pg 1720-1721.
- Stein DM, Knight WA 4th. Emergency Neurological Life Support: Traumatic Spine Injury. Neurocrit Care. 2017;27(Suppl 1):170-180. doi:10.1007/s12028-017-0462-z
Title image, taken from Wikimedia Commons, is licensed under a Creative Commons Attribution 3.0 Unported License.
Whats the rationale behind keeping MAP that high ?
Great question! Current National Guidelines recommend maintaining a MAP between 85-90 mmHg for at least seven days whenever a Spinal Cord Injury is suspected. The current hypothesis is that by avoiding lower MAP’s, we could prevent Spinal Cord ischemia and consequently avoid further injury and disability. However, these guidelines are based on retrospective and observational studies. There is currently a randomized trial in progress that exactly questions this practice, so we hope to get a more definitive answer soon.
Epinephrine Vs Norepi?
High Vs Normal MAP?
Hello Siva,
Norepinephrine is the vasopressor of choice in Neurogenic Shock as it has the same effect as other pressors, but with less adverse effects. Remember that the underlying pathophysiology in Neurogenic Shock is the interruption of the sympathetic chain resulting in unopposed vagal tone and a distributive shock picture (Hypotension and bradycardia). Norepinephrine Has both alpha and some beta activity, thereby improving both peripheral vasoconstriction and inotropy. Current National Guidelines recommend maintaining a MAP between 85-90 mmHg for at least 7 days after a Spinal Cord Injury is suspected and diagnosed.
I hope this helps.